The determination of molecular structures of organic molecules in a geological formation, such as kerogen or coal, is known. Some of these conventional determinations are based on nuclear magnetic resonance measurements taken at the geological formation.
A first step in a convention technique a high-resolution 13C CP/MAS spectrum of a given sample is obtained, and then a plurality of different cutoffs are applied to the spectrum in discrete processes in order to determine the mole fraction of different sets of molecular structures and dynamics (e.g., aromatic and aliphatic carbons; methyl group, ethylene/methine group, and methoxy group in aliphatic regime; carbonyl carbons and aromatic carbons; aldehyde/ketone and acid/ester amide groups; protonated and non-protonated aromatic rings; and bridge heads, alkyl-attached aromatic rings, and phenols/phenolic esters; and/or other structures). These discrete processes can time-consuming and costly with respect to computing and/or human resources. Conventional techniques may assume NMR spectra comes from a pure sample that all molecules have same structure. Conventional techniques typically do not measure and/or use the shapes of static and dynamic parameter distributions, which characterize the heterogeneity of molecular structures and variation of molecular mobility.
One aspect of the disclosure relates to a computer-implemented method of determining molecular structures of organic molecules in a geological formation. The method is implemented in a computer system comprising one or more physical processors configured to execute computer program modules. The method comprises obtaining a plurality of chemical shift spectra derived from nuclear magnetic resonance measurements taken at the geological volume of interest for a plurality of different lengths of a mixing time, wherein a given chemical shift spectrum has been derived from nuclear magnetic resonance measurements for a mixing time that corresponds to the given chemical shift spectrum; applying a transformation to the plurality of chemical shift spectra that yields a multi-dimensional distribution of intensity as a function of chemical shift and one or more dynamic parameters of the nuclear magnetic resonance measurements, wherein the transformation is applied individually to separate sets of chemical shift measurements having common chemical shift values such that the transformation comprises for a given chemical shift value: obtaining, from across the plurality of chemical shift spectra, the measurements of intensity at the given chemical shift value and the values of the mixing time at which the measurements were obtained; and inverting the measurements of intensity at the given chemical shift to provide intensity as a function of the one or more dynamic parameters for the given chemical shift, wherein such inversion comprises performance of a Laplace transform; and determining molecular structures of the organic molecules in the geological formation based on an analysis of the multi-dimensional distribution of intensity and its shape.
A system configured to determine molecular structures of organic molecules in a geological formation. The system comprising one or more processors configured to execute computer program modules. The computer program modules comprising a spectrum module, a transformation module, and an analysis module. The spectrum module is configured to obtain a plurality of chemical shift spectra derived from nuclear magnetic resonance measurements taken at the geological volume of interest for a plurality of different lengths of a mixing time, wherein a given chemical shift spectrum has been derived from nuclear magnetic resonance measurements for a mixing time that corresponds to the given chemical shift spectrum. The transformation module is configured to apply a transformation to the plurality of chemical shift spectra that yields a multi-dimensional distribution of intensity as a function of chemical shift and one or more dynamic parameters of the nuclear magnetic resonance measurements. The transformation module is configured such that the transformation is applied individually to separate sets of chemical shift measurements having common chemical shift values such that the transformation comprises for a given chemical shift value: obtaining, from across the plurality of chemical shift spectra, the measurements of intensity at the given chemical shift value and the values of the mixing time at which the measurements were obtained; and inverting the measurements of intensity at the given chemical shift to provide intensity as a function of the one or more dynamic parameters for the given chemical shift, wherein such inversion comprises performance of a Laplace transform. The analysis module is configured to determine molecular structures of the organic molecules in the geological formation based on an analysis of the multi-dimensional distribution of intensity.
Non-transitory electronic storage media storing processor executable instructions configured to cause one or more processors to execute a method of determining molecular structures of organic molecules in a geological formation. The method comprising obtaining a plurality of chemical shift spectra derived from nuclear magnetic resonance measurements taken at the geological volume of interest for a plurality of different lengths of a mixing time, wherein a given chemical shift spectrum has been derived from nuclear magnetic resonance measurements for a mixing time that corresponds to the given chemical shift spectrum; applying a transformation to the plurality of chemical shift spectra that yields a multi-dimensional distribution of intensity as a function of chemical shift and one or more dynamic parameters of the nuclear magnetic resonance measurements, wherein the transformation is applied individually to separate sets of chemical shift measurements having common chemical shift values such that the transformation comprises for a given chemical shift value: obtaining, from across the plurality of chemical shift spectra, the measurements of intensity at the given chemical shift value and the values of the mixing time at which the measurements were obtained; and inverting the measurements of intensity at the given chemical shift to provide intensity as a function of the one or more dynamic parameters for the given chemical shift, wherein such inversion comprises performance of a Laplace transform; and determining molecular structures of the organic molecules in the geological formation based on an analysis of the multi-dimensional distribution of intensity.
These and other objects, features, and characteristics of the system and/or method disclosed herein, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. As used in the specification and in the claims, the singular form of “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.